ASTM D2913-96
(Test Method)Standard Test Method for Mercaptan Content of the Atmosphere
Standard Test Method for Mercaptan Content of the Atmosphere
SCOPE
1.1 This test method covers measurement of the concentration of mercaptans (organic thiols) in the atmosphere at concentrations below 100 parts per billion (ppb(v) = 195 µg/m3). For concentrations above 100 ppb(v) level, the sampling period can be reduced or the liquid volume increased either before or after aspirating. The minimum detectable amount of methyl mercaptan is 0.04 µg/mL (1) in a final liquid volume of 25 mL. When sampling air at the maximum recommended rate of 2 L/min for 2 h, the minimum detectable mercaptan concentration is 1.0 ppb(v) (1.95 µg methyl mercaptan/m 3 at 101.3 kPa (760 mm Hg) and 25oC). This test method determines total mercaptans and does not differentiate among individual mercaptans, although it is most sensitive to the lower molecular weight alkanethiols.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 8.7, 8.8, and Section 9.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2913 – 96 An American National Standard
Standard Test Method for
Mercaptan Content of the Atmosphere
This standard is issued under the fixed designation D 2913; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3609 Practice for Calibration Techniques Using Perme-
ation Tubes
1.1 This test method covers measurement of the concentra-
D 3631 Test Methods for Measuring Surface Atmospheric
tion of mercaptans (organic thiols) in the atmosphere at
Pressure
concentrations below 100 parts per billion (ppb(v) = 195
E 1 Specification for ASTM Thermometers
μg/m ). For concentrations above 100 ppb(v) level, the sam-
pling period can be reduced or the liquid volume increased
3. Terminology
either before or after aspirating. The minimum detectable
2 3.1 Definitions—For definitions of terms used in this test
amount of methyl mercaptan is 0.04 μg/mL (1) in a final liquid
method, refer to Terminology D 1356.
volume of 25 mL. When sampling air at the maximum
recommended rate of 2 L/min for 2 h, the minimum detectable
4. Summary of Test Method
mercaptan concentration is 1.0 ppb(v) (1.95 μg methyl
3 4.1 This test method is intended for obtaining an integrated
mercaptan/m at 101.3 kPa (760 mm Hg) and 25°C). This test
sample over a selected time span (such as 2 h) either manually
method determines total mercaptans and does not differentiate
or in an automatic sequential sampler using 10 mL of absorp-
among individual mercaptans, although it is most sensitive to
tion liquid in a bubbler.
the lower molecular weight alkanethiols.
4.2 The absorption liquid is delivered to the laboratory for
1.2 The values stated in SI units are to be regarded as the
colorimetric analysis by reaction between the collected mer-
standard.
captan and N,N-dimethyl-p-phenylenediamine.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 Mercaptans are odorous substances offensive at low
priate safety and health practices and determine the applica-
concentrations and toxic at higher levels. They are emitted
bility of regulatory limitations prior to use. Specific precau-
from geothermal sources, industrial processes, and food pro-
tionary statements are given in 8.7, 8.8, and Section 9.
cessing facilities.
2. Referenced Documents
6. Interferences
2.1 ASTM Standards:
3 6.1 The N,N-dimethyl-p-phenylenediamine reaction is also
D 1193 Specification for Reagent Water
suitable for the determination of other sulfur-containing com-
D 1357 Practice for Planning the Sampling of the Ambient
4 pounds including hydrogen sulfide and dimethyl disulfide (2).
Atmosphere
The potential for interference from these latter compounds is
D 1914 Practice for Conversion Units and Factors Relating
especially important, since all of these compounds commonly
to Sampling and Analysis of Atmospheres
coexist in certain industrial emissions. Appropriate selection of
D 2914 Test Methods for Sulfur Dioxide Content of the
the color formation conditions and measurements of absor-
Atmosphere (West-Gaeke Method)
bance at the specified wavelength will eliminate the potential
D 3195 Practice for Rotameter Calibration
interference from hydrogen sulfide.
D 3249 Practice for General Ambient Air Analyzer Proce-
6.2 Hydrogen sulfide, if present in the sampled air, may
dures
cause a turbidity in the sample absorbing solution. This
precipitate must be filtered before proceeding with the analysis.
One study showed that 100 μg of H S gave a mercaptan color
This test method is under the jurisdiction of ASTM Committee D-22 on
equivalent to 1.5 to 2.0 μg of mercaptan (3). Another study
Sampling and Analysis of Atmospheres and is the direct responsibility of Subcom-
reported no absorption at 500 nm in the presence of 150 μg of
mittee D22.03on Ambient Atmospheres and Source Emissions.
hydrogen sulfide (4, 5).
Current edition approved April 10, 1996. Published June 1996. Originally
e1
published as D 2913 – 70 T. Last previous edition D 2913 – 87 (1991) .
6.3 Approximately equimolar response is obtained from the
The boldface numbers in parentheses refer to the list of references at the end of
hydrolysis products of dimethyl disulfide, the molar extinction
this test method.
Annual Book of ASTM Standards, Vol 11.01.
4 5
Annual Book of ASTM Standards, Vol 11.03. Annual Book of ASTM Standards, Vol 14.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2913
coefficient for the amine-mercaptan reaction product being activated charcoal to prevent recirculating small quantities of
4.4 3 10 , and the amine-dimethyl disulfide reaction product mercaptans. See Practice D 3609 for details.
being 5.16 3 10 (5). The interference due to dimethyl disul- 7.3 Colorimeter or Spectrophotometer, (at 500 nm)—Use
fide has been experimentally determined. Dimethyl disulfide 2.5- or 5.0-cm path length to obtain adequate sensitivity.
concentrations of 0.6 ppm(v) and 1.0 ppm(v) given an equiva-
8. Reagents and Materials
lent response as 0.4 ppm(v) and 0.8 ppm(v), respectively, of
methyl mercaptan.
8.1 Purity of Reagents—Reagent grade chemicals shall be
6.4 Sulfur dioxide up to 250 μg does not influence the color used in all tests. All reagents shall conform to the specifications
development even when sampling a test atmosphere containing
of the Committee on Analytical Reagents of the American
300 ppm(v) of SO . Chemical Society, where such specifications are available.
6.5 Nitrogen dioxide does not interfere up to 700 μg of NO
Other grades may be used, provided it is first ascertained that
when sampling a test atmosphere containing 6 ppm. Higher the reagent is of sufficiently high purity to permit its use
concentrations of NO caused a positive interference when without lessening the accuracy of the determination.
mercaptans were present, but no interference in the absence of 8.2 Purity of Water—Unless otherwise indicated, references
mercaptans. Such elevated NO concentrations are unrealistic to water shall mean referee reagent water conforming to
and would not be encountered in the ambient air except in the Specification D 1193.
vicinity of an accidental spillage. 8.3 Solutions should be refrigerated when not in use.
6.6 The supply of mercuric acetate must be free of mercu- 8.4 Amine-Hydrochloric Acid Solution, Stock—Dissolve 5.0
rous ion. If mercurous ion is present, turbidity will result when gof N,N-dimethyl-p-phenylenediamine hydrochloride (p-
the chloride ion-containing reagents are added in the last step
aminodimethylaniline hydrochloride) in 1 L of concentrated
of the analytical procedure. hydrochloric acid (HCL). Refrigerate and protect from light.
This solution is stable for at least 6 months.
7. Apparatus
8.5 Reissner Solution—Dissolve 67.6 g of ferric chloride
7.1 Sampling Apparatus: hexahydrate (FeCl ·6H O) in distilled water, dilute to 500 mL,
3 2
7.1.1 Absorber—Midget bubbler with coarse porosity frit. and mix with 500 mL of nitric acid (HNO ) solution containing
7.1.2 Air Sample Probe—TFE-fluorocarbon, polypropy- 72 mL of boiled concentrated nitric acid (sp gr 1.42). This
lene, or glass tube with a polypropylene or glass funnel at the solution is stable.
end. 8.6 Color-Developing Reagent—Mix 3 volumes of amine
7.1.3 Moisture Trap-Glass, or polypropylene tube with a solution and 1 volume of Reissner solution. Prepare this
two port closure. The entrance port of the closure is fitted with solution freshly for each set of determinations.
tubing that extends to the bottom of the trap. The unit is loosely 8.7 Absorbing Solution—Dissolve 50 g of mercuric acetate
packed with 16-mesh activated charcoal to prevent moisture Hg (CH COO) in 400 mL of distilled water and add 25 mL of
3 2
entrainment. The charcoal should be changed weekly. glacial acetic acid (CH COOH). Dilute to 1 L. The mercuric
7.1.4 Filter—Membrane, of 0.8 to 2.0 μm porosity. acetate must be free of mercurous salts to prevent precipitation
7.1.5 Pump—Capable of maintaining a vacuum greater than of mercurous chloride during color development. Reagent
70 kPA (0.7 atm) at the specified flowrate. grade mercuric acetate sometimes contains mercurous mer-
7.1.6 Flow Control Device—A needle valve capable of cury. Determine the acceptability of each new bottle of
maintaining a constant flow rate (62 %). Protect the needle mercuric acetate by adding 3 mL of concentrated hydrochloric
valve from particulate matter and moisture entrainment. acid to 3 mL of the 5 % mercuric acetate. If the solution
7.1.7 Flow meter, having a range of 0 to 2.5 L/min. becomes cloudy, the mercuric acetate is not acceptable.
7.1.8 Thermometers—ASTM Thermometer 33C, meeting (Warning—The absorbing solution and mercury salts are very
the requirements of Specification E 1, will be suitable for most poisonous. Avoid contact with the skin and especially with the
applications of this test method. eyes. Avoid generating or breathing dust. Wash hands after use.
7.1.9 Barograph or Baro
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.